


It's a Sin

by TheRedPoet



Category: The Locked Tomb Trilogy | Gideon the Ninth Series - Tamsyn Muir
Genre: F/F, Highschool AU, but with teachers, no beta we die like cavaliers
Language: English
Status: Completed
Published: 2021-03-19
Updated: 2021-03-26
Packaged: 2021-03-28 22:07:06
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 3,389
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/30146289
Author URL: https://archiveofourown.org/users/TheRedPoet/pseuds/TheRedPoet
Summary: Harrowhark has graduated highschool, fought her way clear of her troubled youth, and earned a teacher's diploma. She's finally starting to get things in order. Enter Gideon Nav.
Relationships: Gideon Nav/Harrowhark Nonagesimus
Comments: 17
Kudos: 59





	1. Chapter 1

**Author's Note:**

> I first got this idea for some Christmas-themed prompt featuring stupid sweaters or some such. I decided on the general concept and setting in Highshool, only with a twist, and got a few details of Gideon's and Harrow's past down... and then I promptly got stuck. I'll readily admit I have no idea whatsoever where I'm going with this, and I don't think I've got Harrow's voice down all that well, but I figure some practise can't hurt before I write something more substantive.
> 
> Enjoy. More to come. I hope.

Harrowhark Nonagesimus was having a good day. It was Friday and she had only just discharged her students from the last lesson of the day. They preceded her into the hallway of Canaan Highschool in an orderly fashion and other students, upon spotting her, ceased any activity they ought not be engaged in in the first place.

It was a far cry from the unruly, poorly disciplined mess she had been handed at the beginning of the term, and Harrow allowed herself a brief moment of pride. She was not entirely worthless. She could accomplish things, make something better, rather than rendering anything she touched ashes and ruination.

A weekend of reading in blessed, peaceful solitude awaited her, but first she would talk to her colleges in the teacher’s lounge, and have a cup of coffee. Not because she particularly liked coffee, but there were some among her co-workers who she considered… if not friends, the closest to the same she’d ever managed. It wouldn’t do to let that go to waste.

So she opened the door, took in the scent of old books, cinnamon and coffee, and then promptly walked straight into something soft but utterly unyielding. She blinked, looked up, and the admonishment she’d been about to level froze upon her tongue as she took in the sight before her.

A tall woman in a pair of simple, comfortable jeans and tank-top. She was built lean, with broad shoulders and defined musculature at her arms. Her hair was a bright orange, carelessly tousled and achingly familiar, and her unmistakable amber eyes were widening in surprise.

“Harrow?”

“Griddle.”

She stared at Harrow. Like a complete moron. Some things clearly hadn’t changed.

“What are you doing here?” Harrow hissed under her breath.

Gideon shrugged with the same infuriating devil-may-care attitude as ever. “I’ve got a year left to study and figured, experience and money, win-win, you know? Get my foot in the door.”

Harrow felt the beginnings of a headache and massaged her temple.

“Allow me to rephrase,” she said, between gritted teeth. “Why are you here?”

“I heard Aiglamine hurt her leg and had to retire. Guess I kinda missed this place, so I sent them my application.”

It had been nearly five years since they’d last seen one another. Five long years and now here Gideon Nav stood, as though nothing had ever happened, as if they were back in high school, as if Harrow hadn’t ruined everything, and-

This day simply couldn’t get any worse.

“Who have we got here, Harry?” Ianthe Tridentarius crooned in her ear.

Gideon’s eyes widened and she mouthed the word ‘Harry?’

Harrow prayed for the Locked Tomb to open, for it to be real, and that it might swallow her whole. Anything was preferable to her current predicament.

“Ianthe…” Harrow began, the words ground out between gritted teeth. “This is Gideon Nav. Gideon Nav. Ianthe Tridentarius.”

Gideon lowered her shades enough to give Ianthe a brief once-over, gave her a nod, and then promptly ignored her. It strangely made Harrow feel better.

“I can’t believe you ended up a teacher,” Gideon said. “Figured you’d be on your way to being a big-shot doctor by now or something.”

“Plans change.”

Gideon considered that for a while and then her expression shifted to something far worse than her usual self-assured swagger. Worse, even, than Ianthe’s snide little smile. 

Pity. 

Harrow would rather have been boiled alive than be subjected to anyone’s pity. Especially Gideon’s.

“Teaching is a noble profession,” she said, jaw clenched so hard it was a miracle the enamel on her teeth didn’t crack.

“Of course,” Gideon agreed. “I’m not saying it isn’t. Just thought you were - you know - dead set on it.”

She chuckled awkwardly at her own pun. Harrow just stared. Had there been a container of boiling water large enough for the task, Harrow felt like she might have gone for it. Or, perhaps, pushed Gideon in instead. Alas, the teacher’s lounge had no person-sized cauldrons full of boiling water.

“As riveting as your reunion is,” Ianthe said. “I’m afraid I have to go prepare for my next lesson. Get some food in you, Harry. You look like you might pass out any second.”

“Go fuck yourself, Tridentarius,” Harrow snapped. She did it quietly enough that John Gaius, headmaster and eternal optimist who thought that perhaps, one day, Harrow and Ianthe might become friends, didn’t hear.

Ianthe’s eyebrows rose and quirked in a way that implied a multitude of depravity and sin so extensive, Harrow felt sullied by sheer proximity.

A moment of silence followed in the wake of her departure.

“Huh,” Gideon said. ”I always thought she seemed like she’d be a bitch. Guess I was right.”

“She’s…” Harrow racked her brain.

“A bitch,” Gideon repeated.

Harrow sighed. “I suppose it’s accurate enough.”

“So… Why is the bitch here? Isn’t she - like - royalty or something? Figured she’d be busy snorting coke and keeping assholes with cameras in a job.”

“Coronabeth,” Harrow said, as though it explained everything. Because it should, to anyone who was not a complete moron. A moment passed. Gideon looked at her, with her attempts to keep her impatience off her face less and less successful. Harrow sighed. “Coronabeth Tridentarius. Ianthe’s sister.”

Gideon kept on looking at her as she once had when they had studied calculus together.

Harrow ground her teeth. “The blonde who did that bikini shoot two years ago.”

Immediate comprehension. Gideon grinned. “Oh yeah. That one got me through many lonely nights, let me tell you.”

“I would rather you didn’t,” Harrow said. “Regardless, she got it in her head that she should get a proper job and mingle with the unwashed masses, and so she did. Ianthe goes wherever Corona does, and now she is here, too.”

“And calling you pet names, apparently.” 

She raised one eyebrow, rather as Ianthe had previously, but as repugnant as the prospect that she might be intimate with Ianthe Tridentarius was, that didn’t distract Harrow from her tone of voice. Was that a note of hurt? Jealousy? Truly, Griddle? “Why do you care?”

Gideon looked around. They weren’t alone in the room but people - and by people, Harrow was excluding Ianthe - seemed to realise they were in the middle of something. With the light buzz of conversations going on all around them they had some modicum of privacy.

“Who says I care?” Gideon asked. “Why would I care?”

Harrow hadn’t the answer. She wished she hadn’t asked. Her throat felt tight and even if she’d known what to say, she didn’t dare to try, lest she betray weakness. She hated weakness, her own more than anyone else’s, and Gideon had always, always brought out the worst kind of weakness in her. The craving to stretch beyond what she already had, beyond what she deserved, to hope that there might be something more.

Gideon was her doom. She was her salvation.

She…

“Why did you leave?” Harrow finally asked.

Gideon looked at her for a long time before she finally spoke. She didn’t look angry, as she once had. Just sad. “You asked me to.”

She had. 

But she hadn’t meant it.


	2. Chapter 2

**Notes for the Chapter:**

> Might be keeping the chapters for this one in these small bit-size chunks and update more frequently. Initially meant to write a longer one, but I liked the cut-off point.

Harrow did not have a good weekend. In point of fact, it was one of the worst she’d had since her first, disastrous practical under Mercymorn, some three years. She hardly slept. She barely ate. Like then, she’d spent Friday evening and all of Saturday considering the box kept locked under her bed. Like then, she’d caved by Sunday. She’d picked up the box. She’d taken the key from its separate hiding place. She’d opened it… and beheld its content. For a short while, it made her smile with fond remembrance. Then, she cried, and did not stop for a long time.

By the time Monday came around, the only thing that kept her from calling in sick was the knowledge that then she might end up receiving a worried call from John Gaius or a visit from Palamedes Sextus. She would rather suffer a week of insinuations about PMS from Ianthe than that.

She studiously avoided the teacher's lounge between lessons and this worked for a short while. On Wednesday, as she took her lunch in a little nook in the exterior wall where students generally snuck off to smoke, she heard the familiar tromp of heavy boots. She shrunk as far into the corner as she could, clutching her bowl of noodles between fingers going numb with the cold. The steps stopped just around the corner. A few seconds went on by,dragging on and on, and Harrow felt her heart pounding in her chest.

Then Gideon appeared, her ridiculous hair pulled back from her face and still wet.

“Who told you?” Harrow asked.

“I mean, I wanna say Ianthe just on the off-chance you decide to murder her…” Gideon shook her head and smiled a little. “This is where you always hung out. Back in the day when you were avoiding… well, everyone.”

It had been. Up until the point that Gideon decided she was going to talk to the weird kid from the weird cult who everyone else treated like a highly contagious leper. She was surprised Gideon had even remembered, though, but Gideon had always had a fine mind for the very few things that genuinely interested her. Approximately ninety-nine percent of which, by sheer coincidence, happened to infuriate Harrow.

“I wanted to be alone.”

Gideon leaned against the wall. With her thick jacket and her broad shoulders she covered most of the opening and Harrow found herself strangely grateful of the fact.

“Then or now?”

“Both.”

“Tough shit,” Gideon said, which was exactly what she’d said that fateful day, nearly ten years ago. “You’re going to catch a cold and die and I’m not spending the rest of my life with you haunting me and scaring away all the ladies.”

Harrow ignored most of that statement and gave Gideon’s hair, which was beginning to freeze, a pointed look.

Gideon sighed dramatically. “I’m more of a do as I say, not as I do, kind of a teacher. Come on, Gloom Minstress. I’ve got a lot of hot ladies to bang in the near future and absolutely no time for cute goth ghosts making them jealous.”

Harrow was experiencing a lot of emotions - most of them directly conflicting with one another. She wasn’t entirely sure what to feel, never mind what to do. As always, Gideon swept into her life like a god damned storm and left everything in a mess.

“Fine,” Harrow said and got to her feet, ignoring Gideon’s offered hand. “Let’s go.”

Gideon made a relieved sound. “Thank God. Ianthe accused me of scaring you off or something. Pretty sure she wants to bone you pretty badly, just so you know, in case you’re into weird mayonnaise chicks or whatever these days, and da- John’s been giving me this sad look like I’m a puppy who crapped in his great grandma’s vase or something.”

“So long as you never, ever speak of any of the depravities Ianthe Tridentarius might wish to subject me to. Ever again.”

Gideon snickered. “Deal.”

She slung an arm around Harrow’s shoulders. The way she had, back in the day. It had taken Harrow weeks to tolerate it… and then considerably less to start enjoying it. Now, she stiffened. Gideon did, too.

“Ah. Shit. Sorry.” Gideon slowly, awkwardly, let go. “Uh. Old habits die hard, I guess?”

Harrow eyed her. “As will you if you try that again.”

She might be able to keep the smile off her face, but some of it came out unbidden in her voice, softening the statement considerably. Gideon grinned.

“Can we try to bury the hatchet? We’re supposed to be adults and shit. Figured it’d be the thing to do.”

Harrow wished it was possible to undo all the things she’d done. All the things she’d said. It wasn’t. Some slates you just couldn’t wipe clean… but she supposed that didn’t mean one shouldn’t try.

“Fine,” she finally said. Then, more softly, almost as an afterthought, she added. “Griddle.”


	3. Chapter 3

It almost frightened Harrow how quickly things returned to a version of normal that she’d thought long-forgotten by both of them. How easily they slipped into habits cultivated over years.

Gideon’s initial offer of giving Harrow a ride home on her motorcycle - the second best ride in town, or so Gideon assured her - Harrow declined.

“I would prefer not to risk whatever brain damage you evidently suffered that robbed you of your sense of self-preservation.”

Two days later, Gideon offered again, and this time she’d brought a second helmet. After which Harrow spent most afternoons clinging to Gideon, fearing each twist and turn of the road nearly as much as how much she enjoyed the warmth and the scent of leather.

Other gestures were smaller, but just as important. They ate together, just as they had in high school. Harrow’s food was much the same. More often than not, noodle soup with most of the spices discarded. Once upon a time, she’d refrained from any spices or additives in her food because such luxuries distracted one from God, and thus, were sinful. Now, she simply found too much taste… difficult to manage.

“One of these days you’re going to be blown away by a stiff breeze,” Gideon said halfway through their third week of working together. “And maybe you’ll be able to roll with that by turning into a bat or something, but it’d probably be better if you just ate more, you know.”

“I am eating,” Harrow said.

“Yeah, but that stuff’s crap. I mean, don’t get me wrong, it’ll do in a pinch… but you need some protein, Harrow. I’m pretty sure you’re the only person here who’s literally skinnier than back in high school.”

Harrow said nothing and as the seconds ticked on by, she thought maybe Gideon had dropped the subject. She sipped her soup with a sense of triumph. Then Gideon reached over and dropped a few torn strips of chicken into her bowl.

Harrow stared at the meat swimming among her noodles and watery broth. Then she looked up at Gideon, who at the very least had the decency to look sheepish. She was about to level a rebuke so vicious Gideon would flee the building, never to return and presume ever again, when the red-head said a single word.

“Please?”

It was soft. A plea, almost. Just like that first time.

It had been at PE. They’d been fourteen or fifteen and already, Gideon was most of a foot taller Harrow. She’d been gangly, back then, all long awkward limbs, and it had been another few years before she began to grow into herself… but she’d still excel at any kind of physical activity by virtue of sheer pig-headed stubbornness. Harrow, on the other hand, had neither the aptitude nor the inclination to play dodgeball or soccer or whatever madness her teachers had decided was on the agenda.

And yet, play she had, because she obeyed and respected her elders and needed as high a grade as possible. She wasn’t sure what had happened. One moment, she’d been chasing the ball, intent on reaching it and at the very least kicking it in the general direction of the opposing team’s goal. The next, her legs had lost their strength and everything had faded into blackness.

She’d woken up some indeterminate amount of time later and found herself insisting very firmly that she was alright and that she could make her way back to class without trouble. The teacher had eventually been convinced, but Gideon had not. They’d found themselves in the locker room afterwards, with Harrow avoiding looking at all the exposed skin almost as fervently as everyone else avoided looking at her, and Gideon had offered her a colourful boxy container with a drinking straw stabbed through the top.

“Drink up,” Gideon said.

Harrow had taken the container, brought the straw to her lips, and sipped slowly. The drink turned out to be orange juice, but sweeter, as though it had… sugar.

Harrow’s eyes had widened and she’d damn near panicked. She shoved the juice box back into Gideon’s hands.

“I can’t,” she whispered, as if her aunts or her parents might be nearby, listening.

Gideon frowned at the juice box, then at Harrow. “Your blood sugar’s all fucked up. You ate jack shit for lunch and you ran your ass off back there - nice job by the way - and you need to recharge.”

Harrow swallowed a mouthful of saliva with the sweet and sour aftertaste of the juice still lingering on her tongue, each complimenting the other so as to not be too overpowering.

“I can’t,” she repeated.

“Why?” In the year they’d known one another, Gideon had remained uncharacteristically tactful about her dietary choices.

“It’s impure,” she’d said, as if that would make sense to Gideon. It obviously hadn’t. “It’s sinful.”

Gideon just frowned and with a single, pleading word, she undid Harrow.

“Please.”

Harrow looked at the juice box. She took it. She embraced sin.

It wouldn’t be the first time. Nor the last.

***

The chicken was lightly seasoned and a little dry, but the subtle taste of lemon pepper and salt wasn’t overwhelming. In the beginning stages of their… arrangement Gideon had brought her all sorts of exotic things, which had rarely been particularly successful. She’d soon realised Harrow’s aversion to things that tasted too much and had adapted. It had been nice. Harrow chewed slowly and tried to ignore how Gideon watched her eat, smiling like nothing in the world made her happier. It was still quite nice. She didn’t admit as much, and never would, but it was.

A plate of soup rattled down on the table next to Harrow and she almost jumped out of her chair. She usually didn’t let anyone - especially Ianthe Tridentarius - sneak up on her. As always, Gideon was proving a dangerous distraction.

“Made up, have we?” Asked Ianthe, looking between them.

Harrow refused to even look her way. “Whatever are you talking about?”

“Your little lover’s quarrel.”

“It is not-”

“Listen here, motherfucker-” Gideon growled and she seemed about to do something along the lines of what she’d done to Silas Ocktaciseron when she’d heard him talk about Harrow. Before any bones were broken, though, John Gaius appeared over Ianthe’s shoulder and Gideon went quiet.

“There you are, Harrowhark,” he said. “And Gideon. How are you settling in?”

Gideon looked from Harrow to Ianthe. “Everyone’s being very… helpful.”

If he noted her decided lack of enthusiasm and deadpan delivery - and Harrow thought it very unlikely that he did not - the headmaster did not comment on it, or even react.

“I’m glad to hear it,” John said. “We’re going to be starting up something of a project. Something of a group effort. You’ll hear more about it next week.”

His tablet beeped and he excused himself.

“Well, well,” said Ianthe. “It seems we’re all going to be working a lot closer soon. What joy.”

There was something about the suggestive curve of her pale lips that irritated and intrigued Harrow. The former being far more prevalent than the later.

Harrow put on her best, pleasant smile. The one she’d practised in the mirror until Camilla had assured her that she only barely looked like a serial killer. “As I said not too long ago… Go fuck yourself, Tridentarius.”

“How I love it when you talk dirty to me, Harry,” Ianthe said. “You’d better be careful or you’ll make Gideon jealous.”

Ianthe hadn’t quite finished her soup, but having the last laugh clearly took priority. In either case, Coronabeth had just arrived and so she moved over to sit with her sister before her sister decided to sit with Harrow.

“What the fuck just happened?” Gideon whispered the moment Ianthe was out of earshot. “Did the two of you just have a moment? Is that what the world’s come to?”

“We did not have a moment,” Harrow said. “I absolutely fucking hate her.”

Gideon snorted. “You said that about me, once.”

“That was different.”

“How?”

There suddenly wasn’t enough air in the room and the words came out as a wheeze. “I never meant it with you.”


End file.
